The present invention relates to inflatable and air fluidized support surfaces for beds. More particularly, the present invention relates to a bed having both air bladders and at least one air fluidized section for supporting a patient which can be easily transported and maneuvered between a very low position in which the support surface is located close to the floor to facilitate patients getting into and out of the bed.
Air fluidized beds have been used as patient support systems. In this type of bed, a fluidizable medium such as tiny spheres formed of glass, ceramics, or silicone is contained within a suitable support and fluidized by air passing through the support mechanism to support the patient. In a common design, the fluidizable medium is supported by a diffuser board which is permeable to air but impermeable to the fluidizable medium. A retaining mechanism which is impermeable to air is positioned around outer edges of the diffuser board. A flexible cover encloses the fluidizable medium and is permeable only to air flow.
Fluidized beds provide an excellent support surface for patients to help prevent formation of bed sores because of the equal distribution of pressure on the support surface. In addition, fluidized beds are well suited for treatment of patients with skin grafts because the fluidized support surface does not produce high shear, frictional forces when the patient moves on the bed.
The present invention includes a modular inflatable and air fluidized bed assembly. The support surfaces of the present invention are similar to those disclosed in U.S. Pat. No. 5,623,736 owned by the assignee of the present application, the specification of which is incorporated herein by reference.
A problem associated with air fluidized beds involves maintaining the temperature of the air fluidized section of the bed below a desired level. The present invention provides an improved cooling mechanism for air flow from a blower through the air fluidized section of the support surface.
According to one aspect of the present invention, a diffuser assembly is provided for supporting a fluidizable medium on a fluidized bed. The diffuser assembly includes a diffuser board which is permeable to air and impermeable to the fluidizable medium, and a metal plate coupled to the diffuser board. The metal plate is formed to include a plurality of apertures therein to permit air to pass through the metal plate.
In the illustrated embodiment, the apparatus includes a ground conductor having a first end coupled to the metal plate and a second end coupled to ground to provide a ground plane. The illustrated metal plate has an outer perimeter edge. The plurality of apertures are spaced inwardly from the outer perimeter edge of the metal plate by a predetermined distance to define a solid border configured to block air flow through the metal plate adjacent the outer perimeter edge. The illustrated fluidized section of the bed includes an outer inflatable portion defining a boundary of the air fluidized section. The predetermined distance is selected so that the air flow through the apertures of the metal plate is spaced inwardly from the outer inflatable boundary of the fluidized bed.
In one illustrated embodiment, a first metal plate is coupled to a top surface of the diffuser board and a second metal plate is coupled to a bottom surface of the diffuser board. The second metal plate is also formed to include a plurality of apertures to permit air to pass through the second metal plate. The first and second metal plates each have an outer perimeter edge. The plurality of apertures are spaced inwardly from the outer perimeter edges of the first and second metal plates by a predetermined distance to define a solid border configured to block air flow through the first and second metal plates adjacent the outer perimeter edges.
According to another aspect of the present invention, a bed includes at least one air fluidized section. The bed also includes a base configured to support air flow control components including at least one of a blower assembly and an electronic controller configured to control air flow to the at least one fluidized section of the bed. The base has a width dimension. The bed also includes a frame configured to support the at least one fluidized section. The frame has first and second support frame members which are spaced apart by a distance greater than the width dimension of the base. The bed further includes a lifting mechanism coupled between the frame and the base. The lifting mechanism is configured to move the frame between an elevated position and a low position in which the first and second frame members pass over the air flow components on the base to permit the frame to be moved to a low position relative to the ground.
In the illustrated embodiment, the lifting mechanism includes a first support member pivotably coupled to the base and slidably coupled to the frame, a second support member pivotably coupled to the frame and slidably coupled to the base, and an actuator configured to move the first and second frame members to lift the frame relative to the base. The actuator includes at least one hydraulic cylinder. The illustrated bed also includes at least one air bladder located adjacent the at least one air fluidized section on the frame.
According to yet another aspect of the present invention, a bed includes a patient support surface having an air zone, a blower configured to supply air to the air zone, and a main heat exchanger coupled between the blower and the air zone. The main heat exchanger is configured to remove heat from air supplied by the blower to the air zone. The bed also includes an auxiliary heat exchanger coupled between the blower and the main heat exchanger.
In the illustrated embodiment, the auxiliary heat exchanger includes a body portion configured to define an air flow path and a plurality of heat exchange fins extending from the body portion. A first set of heat exchange fins extends outwardly from the body portion of the auxiliary heat exchanger, and a second set of heat exchange fins extends inwardly from the body portion into the air flow path. The body portion and the fins are illustratively made from a metal material.
In one illustrated embodiment, a housing surrounds the body portion of the auxiliary heat exchanger, and a fan is configured to blow air over the body portion. In another illustrated embodiment, at least one fan is coupled to the fins of the auxiliary heat exchanger to blow air over the outwardly extending fins. At least one fin is formed to include a mounting portion configured to receive a fastener to secure the fan directly to the heat exchanger.
A heater is located in an air flow passageway between the blower and the air zone of the bed. The bed further includes a controller coupled to the main heat exchanger, the auxiliary heat exchanger, and the heater to control the temperature of the air zone.
According to a further aspect of the present invention, a caster locking apparatus is provided for a caster that is rotatably mounted to a bed frame member by a support including a notched portion. The locking apparatus includes a housing coupled to the caster. The housing includes an interior region having a top opening located adjacent the notched portion of the support, and first and second notched portions spaced apart from the top opening. The first notched portion is located a first distance from the top opening of the housing, and the second notched portion is located a second distance from the top opening of the housing. The second distance is less than the first distance. The apparatus also includes a locking pin located within the interior region of the housing, a spring configured to bias the locking pin upwardly into the notched portion of the frame to prevent rotation of the caster relative to the frame member, and a stop coupled to the pin. The pin and stop are movable from a first position in which the stop is located within the first notched portion of the housing to compress the spring and remove the pin from the notched portion of the frame to permit rotation of the caster relative to the frame, and a second position in which the stop is located in the second notched portion of the housing to permit the spring to bias the pin upwardly into the notched portion of the frame and lock the caster relative to the frame member.
According to a still further aspect of the present invention, a pilot operated check valve is configured to be positioned inside a fluid supply tube connected between an air supply manifold and an air zone located on a support surface of a bed. The pilot operated check valve apparatus includes a body having an air inlet and an air outlet connected by an air passageway. The apparatus also includes a valve member configured to move between an open position and a closed position to block air flow through the passageway, a push rod having a first end coupled to the valve member to unseat the valve member when the valve member is in its open position and a second end, a diaphragm located in a chamber of the body adjacent the second end of the push rod, and an inlet port configured to be coupled to the manifold to admit pressure against the diaphragm. The body is formed to include a vent hole located on an opposite of the diaphragm from the inlet port. The vent hole is formed in communication with the chamber to permit air passing into the chamber from the air passageway to vent to atmosphere.
Additional objects, features, and advantages of the invention will become apparent to those skilled in the art upon consideration of the following detailed description of the illustrated embodiment exemplifying the best mode of carrying out the invention as presently perceived.